1. Field of the Invention
The present invention concerns an apparatus for handling layers of palletized goods and of the kind indicated in the preamble of claim 1.
2. Description of the Prior Art
In order to provide effective and cheap distribution of goods, many goods are distributed on pallets, by way of example on so-called EU pallets (800×1200 mm). Yet a continuing increasing need has appeared for also dispatching orders comprising smaller consignments of goods in a correspondingly efficient way. Statistically it has appeared that many orders for small shops actually consist of consignments of goods often consisting of very few layers or maybe just a single layer of palletised goods.
WO 2000/64790 A1 and WO 2008/019691 A1 disclose apparatuses for handling layers of palletized goods. These apparatuses comprise a vertically displaceable lift head with a horizontal suction face which in size is adapted to a pallet and has a large number of downwards open suction chambers. The suction face is arranged to be moved downwards against the top side of an upper layer of individually or groupwise packed goods on a pallet, where the suction chambers via individual valves are connected with a source of vacuum incorporated in the lift head. These the apparatuses interact with depalletizing systems which are known per se.
The valves between the suction chambers and the source of vacuum are designed as ball valves with very light thin-walled valve bodies that are enclosed in the suction chamber by lateral projections or by a retainer net which interact with upper round valve openings with spherical valve seats at the bottom if the actual suction chamber is not closed at the bottom by contacting the top side of the goods in an upper pallet layer.
Along the outer sides of the suction face, the lift head comprises a squeezing mechanism for exerting an inwardly pressure at the outer sides of the goods in at least an uppermost pallet layer. In connection with each valve there are arresting means for preventing the valve balls from shutting off the valves, which ensure that the shut-off valves of the suction face can be forcibly opened where there is a contact to the goods in the pallet layer, and can be forcibly opened where there are gaps or openings in the pallet layer. The descriptions of these previous inventions are hereby incorporated in the present application by reference.
In connection with the hitherto common handling of layers of palletized goods, they primarily work with rectilinear lifting and moving of pallet layers, by moving pallet layers mutually between positions on mutually perpendicular pallet ways.
Experiments have been made using robot technology for moving palletized layers of goods by the current suction heads. However, using robots requires an entirely different movement pattern which also includes swinging movements of suction heads, which place significantly greater demands on the suction ability in order to hold the relatively heavy and possibly open pallet layer in a secure way during swinging movements where centrifugal force actions occur.